Re: [json] JSON representation of common types

I ve done some test on that, and almost all simple web services that offer JSON as output could be compiled using the XSD compiler inside .NET SDK, what was

Message 1 of 19
, Jul 17, 2006

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I've done some test on that, and almost all simple web services that
offer JSON as output could be compiled using the XSD compiler inside
.NET SDK, what was missing is always the response class. In my Yahoo!
example (http://weblogs.asp.net/mschwarz/) I was missing the ResultSet
class, which I wrote at my own. All other classes could be created
using the XML schema. The only thing is that Yahoo! i.e. doesn't use
the same data type for JSON as defined in the XML schema.

Do you we need a new schema or can we use XML schema (the light way).
I would be very interessted in having a schema for JSON, too.

> I've done some test on that, and almost all simple
> web services that
> offer JSON as output could be compiled using the XSD
> compiler inside
> .NET SDK, what was missing is always the response
> class. In my Yahoo!
> example (http://weblogs.asp.net/mschwarz/) I was
> missing the ResultSet
> class, which I wrote at my own. All other classes
> could be created
> using the XML schema. The only thing is that Yahoo!
> i.e. doesn't use
> the same data type for JSON as defined in the XML
> schema.
>
> Do you we need a new schema or can we use XML schema
> (the light way).
> I would be very interessted in having a schema for
> JSON, too.
>
> Regards,
> Michael
>
>
>
>
> On 7/17/06, Fang Yidong <fangyidong@...>
> wrote:
> >
> >
> >
> >
> >
> >
> >
> >
> > Common datatypes seem to be a good idea. Maybe we
> can
> > do 'JSON schema'? :-)
> >
> > But as to XML schema, I think it's too
> complicated.
> >
> > --- Michael Schwarz <michael.schwarz@...>:
> >
> >
> > > Because I'm currently using .NET data types in
> my
> > > JSON parser, do you
> > > think it would be a good idea to use common data
> > > type identifiers like
> > > used in XML schema?
> > >
> > >
> >
>

I ve been doing some thinking along these lines for my work on the JSON-RPC 1.1 specification. In JSON-RPC 1.1, I added introspection support for services,

Message 5 of 19
, Jul 17, 2006

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I've been doing some thinking along these lines for my work on the
JSON-RPC 1.1 specification. In JSON-RPC 1.1, I added introspection
support for services, meaning that there would be a standard way to
describe a service, its procedures and the paramterers of those
procedures. Needless to say, the last bit needs some type-hinting
support, especially for the strongly-typed languages so that they have a
chance of generating reasonable proxy code. I am not completely done
with all the ideas, but I can shed some light on what I've come up with
so far.

JSON supports 6 data types. As everyone probably can guess, these are
Object, Array, String, Number, Boolean and Null. In JSON-RPC 1.1, these
take the form "object", "array", "string", "number", "bool" and "null"
in text. Dead simple so far, but now let's get to the fun part. From
this, how do you express types representing an array of integers versus
an array of floats? How do you express a type for dates expressed in ISO
8601 format versus those in Unix time? The first rule I came up with is
not to violate or hide the 6 JSON types. These should always be stated
as the root relation of some new type so that parties that don't
understand the extension can still work with the basic ones they know
about. In other words, you express a new data type as specialization of
one of the 6 fundamental types. The type specification expression looks
roughly like this:

If you think about it, it looks a lot like MIME-type specification, as
in "text/plain". This is no coincidence. I wanted a familiar syntax so
that people can pick it up quickly and recall it easily. Short of
writing the spec here, the best way to demonstrate how it works is by
showing you a few examples, so here are some concrete ones I have been
working on:

* string/w3time = String containing time using ISO 8601 format.
* string/time = String containing time using unix time format.
* string/guid = String containing a GUID.
* number/time = Number containing time using unix time format.
* number/int32 = Number that is a 32-bit integer.
* number/int64 = Number that is a 64-bit integer
* number/float = Number with single precision.
* number/double = Number with double precision.
* number/decimal = Number for financial application.
* array/string = Array of String values.
* array/object = Array of Object values.

You can also now combine to form further hierarchies, which is mostly
useful in the Array case, as in:

The important thing to realize is that a consumer can stop processing at
the first slash and take only the pure JSON type on its left if it
wishes to ignore the rest. What's more, it can do this without fear of
loosing information that will be held in the containing super type. For
example, if a consumer treats "string/w3time" as String then the time
information has not been lost. It's just delivered to the application as
a String as opposed to a type that is more representative of time in the
development language of the application.

In the case of Object, it would be possible to say, "object/person",
provided that you describe person somewhere as:

In the last case, you see that "children" is defined as array of
"person" Object values.

Finally, as common sense would tell us, so goes the rule...types such as
Null and Boolean cannot be specialized. A consumer would simple ignore
any specialization.

Anyway, there you have it. Hope I've been able to give an idea of how I
am planning to solve the problem for JSON-RPC 1.1, but it certainly has
a wider application and you're free to see if it fits your needs (as in
describing the column types of a table of records). Meanwhile, I've
tried to keep it simple and effective while allowing for fallback cases.
Thoughts?

I think, simplicity in mind, JSON is not strong-typed, types are only Variants in JSON. I think, we only have, null, true/false, number and string (and we

Message 7 of 19
, Jul 18, 2006

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I think, simplicity in mind, JSON is not strong-typed, types are only "Variants" in JSON. I think, we only have, null, true/false, number and string (and we also have Array and Object structures). So we can only use these types in JSON-Schema.

There is no date, float, function and other primitive/complex types.

I think, JSON-Schema should be simple and it should contain only the basic types/definitions.
JSON-Schema can have, Constraints (May contain regular expressions - this way Date/Time or float types can be handled), Min-Max validations and definition of Object and Arrays...

I admit that, I use Date and "function" or any other JavaScript types in my code, but I don't call them JSON (Well I decided to not to, after becoming a member of this group).
For example adding Dataset to JSON is not possible, it could only be a "recommendation".

Hey, what about J(SON)Pointer and J(SON)Include like XPointer and XInclude? Well that's another topic but something interesting.

I am wondering, if we should keep JSON simple or add more extensions and make it complex?Mert

Because I'm currently using .NET data types in my JSON parser, do youthink it would be a good idea to use common data type identifiers likeused in XML schema?http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/#built-in-datatypesRegards,MichaelOn 7/17/06, Fang Yidong <fangyidong@...> wrote:>>> If used in general purpose,maybe it's good to add the> table name and the field datatypes in the metadata> section.>> --- Mert Sakarya <msakarya@...>:>>> > Hi, I am using readonly datasets in the following> > format;> >> > {> > "DataSet" : {> > "Tables" : [> > {> > "Fields" : ["Column1","ImgDate","Column2"],> > "Records" : [> > ["16.7.2006,Pazar","16.7.2006,Pazar",51],> > ["9.7.2006,Pazar","9.7..2006,Pazar",54],> > ...> > ]> > }> > ]> > },> > "Parameters" : { //Any other you want to return,> > total number of records...> > "RETURN_VALUE" : "0"> > }> > }> >> >> >> >> > Mert Sakarya>> > IT Direkt鰎�>> >> >> >> > Tel> > : (212) 251 85 70 / 112> > Fax> > : (212) 251 89 50> > www.yenibiris.com> >> > ________________________________________> > From: json@yahoogroups.com> > [mailto:json@yahoogroups.com] On Behalf Of Todd> > Sent: Thursday, July 13, 2006 12:02 AM> > To: json@yahoogroups.com> > Subject: RE: [json] JSON representation of common> > types> >> > Thanks for the great feedback Atif.> >> > But I'm really not looking to introduce behavior> > into JSON at all. I don't> > think we even need to get that in depth in order to> > outline a basic way of> > returning the data inside the DataSet.> >> > A DataSet may be an object specific to .NET but each> > language has some form> > of object that represents data returned from a> > database. They may be known> > by a different names, get referenced with different> > syntax, and have> > slightly different behaviors associated with them.> > However, at the most> > fundamental level they are approximately the same> > thing, that being, a> > "flat" 2 dimensional data object (containing columns> > and rows).> >> > My thought is not to duplicate all the "behavioral> > baggage". It is simply to> > take that data (columns and rows) and decide on a> > uniform way of> > representing it within JSON.> >> > In reality there are only two ways to look at> > DataSets, QueryBeans,> > Whatever.....> >> > 1. An Array of Objects (where each object has an> > identical set of keys)> > 2. An Object of Arrays (where each array can be> > assumed to be of the> > exact same length)> >> > These objects can also be returned at the root level> > or nested down inside a> > "wrapper" object that contains "supporting" key> > values such as column Lists,> > record counts, etc...> >> > Everyone who has ever written a JSON parser has come> > up with (in their own> > mind) a great way of doing this already. I simply> > feel it would be helpful> > to the JSON community as a whole, if we all decided> > on ONE way and everyone> > stick to that.> >> > Who gets to decide on what the standard is? I don't> > know. I'm just trying> > to start some dialog and get people thinking about> > it.> >> > Again, maybe I'm way off track here. But it my mind> > it would be helpful to> > know I can write some JavaScript that dynamically> > iterates through an object> > and know it won't break regardless of what parser> > encoded the string.> >> > Just a thought ;)> >> > _____> >> > From: json@yahoogroups.com> > [mailto:json@yahoogroups.com] On Behalf Of Atif> > Aziz> > Sent: Tuesday, July 11, 2006 10:08 AM> > To: json@yahoogroups.com> > Subject: RE: [json] JSON representation of common> > types> >> > I think you'll have a hard time getting input on> > standardization of DataSets> > because most folks who are not familiar with .NET> > Framework may have no clue> > what's being talked about. The DataSet type and> > concept carries a lot of> > structural and behavioral baggage with it. Unless> > one defines the general> > problem (without referring to library-specific> > types) that needs to be> > addressed and then keep the focus on the wire> > format, it's a lost cause. The> > DataSet is specific to the .NET Framework and what's> > mostly interesting> > about it is all the richness it provides to give> > nearly the sense of a> > disconnected database (short of stored procedures> > and a query language> > unless XPath cuts it for your case). Since JSON is> > not about behavior, one> > has to focus on the structure and the wire format.> > The behavior can be> > defined only through an abstract specification that> > defines a processing> > model for each end of the wire that wants to> > interoperate on that data. And,> > mind you, the more you put in there, the more> > behavior each party has to> > provide. For example, if you're going to ship over a> > DataSet in JSON to a> > Java application, then who's going through the> > trouble of making sure that> > something on the Java or JavaScript side can provide> > all the expected> > functionality, like producing updategrams when> > calling back into the server?> > Don't get me wrong. There's an interesting problem> > domain behind it all> > that's interesting to try and standardize, but I> > fear that it might be a bit> > out of scope for this group.> >> > ________________________________> >> > From: json@yahoogroups.> > <mailto:json%40yahoogroups.com> com> > [mailto:json@yahoogroups.> > <mailto:json%40yahoogroups.com> com] On Behalf Of> > 2> > Sent: Tuesday, July 11, 2006 6:10 PM> > To: json@yahoogroups.> > <mailto:json%40yahoogroups.com> com> > Subject: RE: [json] JSON representation of common> > types> >> > Good question.> >> > Unless I'm mistaken a Dictionary is pretty much an> > associative array, which> > will follow the pattern of:> > {key:value,key:value,key:value}, and Lists will> > just be arrays [value,value,value]> >> > I know there is no standard for DataSet or DateTime.> > I started a thread> > about a DataSet standard and got some good feedback> > on the way people like> > to see them, but I didn't really get a strong sense> > of urgency about the> > subject of standardizing them. You can check out the> > thread here:> > http://groups.> > <http://groups.yahoo.com/group/json/message/436>> > yahoo.com/group/json/message/436 <http://groups.> > <http://groups.yahoo.com/group/json/message/436>> > yahoo.com/group/json/message/436>> >> > As for DateTime, again there is no formal standard> > other then just returning> > your data in a format that can be considered a date> > by both languages you> > are developing for (let's say C# and JavaScript).> >>> === message truncated ===>> --> JSON: Action in AJAX!>> JSON - http://www.json.org> JSON.simple - http://www.json.org/java/simple.txt>>>>>>> __________________________________________________________> Mp3疯狂搜-新歌热歌高速下> http://music.yahoo.com.cn/?source=mail_mailbox_footer>>>>>>> -- Best regards | Schöne GrüßeMichaelMicrosoft MVP - Most Valuable ProfessionalMicrosoft MCAD - Certified Application Developerhttp://weblogs.asp.net/mschwarz/http://www.schwarz-interactive.de/mailto:info@...

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Andy

Hi, I went to the root of the conversation since I couldn t find a good spot elsewhere for this thought: I think JSON is fine as-is. If you want something

Message 8 of 19
, Aug 7 11:10 AM

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Hi,
I went to the root of the conversation since I couldn't find a good
spot elsewhere for this thought:
I think JSON is fine as-is. If you want something that can carry more
complicated data types, use XML. If you want something simple, use
JSON. If you're after something in the middle, make up something new.

The way JSON defines types is by its delimiters.
Currently, we have {} for objects, [] for arrays, "" for strings and
nothing for numbers, and true, false, and null stand alone.
If you wish to add more strict data types, you need to add more
delimiter choices. Perhaps Parenthesis should be used for Dates ()
and angle brackets <> for another type. The question eventually
becomes, when are there enough?

Incorporating limits for values is beyond the scope of JSON as a data
serializer. The point of JSON is to efficiently get data from here to
there. The end-points are responsabile for understanding the
capabilities and limitations of the data. If you need to communicate
those, do so in a separate set of correspondance. This can either be
off-line in some agreement, talking to yourself while making up an
AJAX app, or through some nifty schema description language. In any
case, don't mix data with schema.

Another way: If I were a bakery, I don't need to tell my courier that
he's sending bread and include direction on how to eat it each time I
send it. I expect the recipient to know how to eat bread, and if he
doesn't, he can come to my shop and ask for any of my wonderful
sandwich recipies, but I don't need to ship my collection of recipies
with every order of bread.

Out of band data for creating types in other languages which don t cleanly/easily support raw javascript types should be done as optional data, which can still

Message 9 of 19
, Aug 8 7:54 PM

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Out of band data for creating types in other languages which don't
cleanly/easily support raw javascript types should be done as optional
data, which can still be encoded as json.

It should be easy enough to take your objects before json encoding,
and run them through a function to turn them into wrapper objects, the
additional data you need being stored in properties, without polluting
json or json-rpc directly.

Assuming you know that the consumer of the data needs these additional
suggestions as to type election, otherwise as Andy said that `burden`
should be on the decoder to figure it out.

--
Matthew P. C. Morley
MPCM Technologies Inc.

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